Loft conversion in Aix-les-Bains.

In Aix-les-Bains, land is scarce and valuable: between Lac du Bourget, the hillsides and a dense town centre, extending at ground level is not always possible — or desirable. Yet many houses have unused space just above the upper floor: the loft. Converting your loft creates living space without encroaching on the garden or applying for a major building permit. It is often the most cost-effective way to gain one or even two extra rooms.

The uses are many: a loft bedroom for a growing child, a quiet study for working from home, a playroom, a library, or a true master suite with dressing room and shower room. Under a well-oriented roof, the slope of the ceiling and the roof windows create a bright, warm atmosphere that few other rooms in the house can offer.

Beyond comfort, converting your loft adds lasting value to your property: every square metre of living space created increases the resale value, in the Aix-les-Bains area where demand remains strong. And because converting a loft almost always means redoing the insulation, it also improves the energy performance of the house. To place this project within a broader approach, discover how we handle house renovation in Aix-les-Bains.

Before any project, one question decides everything: is your loft really suitable for conversion? The first criterion is the ceiling height. You need at least 1.80 m under the ridge purlin, over a sufficient area, to get a comfortable room. Below that, the space exists but does not count as living space: it is used for storage or circulation.

The second criterion is the roof pitch. The steeper it is (above 35 to 45°), the more generous the usable central volume. A shallow pitch greatly reduces the area that can actually be used on either side of the ridge.

The third criterion is the type of roof structure. A traditional roof structure, with its large timber members around the edges, often leaves a clear central volume: it is ideal for conversion. Conversely, a prefabricated trussed roof (the small timber W-shapes that fill the whole loft) requires structural alterations — the trusses are replaced by a structure that transfers the loads to the edges to free up the space. It is more technical, but entirely feasible.

Finally, you need to make sure the floor is load-bearing. The original joists, often sized for a simple attic, must be checked and, if necessary, strengthened to take a living room, its partitions, its furniture and its occupants. During our visit in Aix-les-Bains, we measure the height, assess the roof structure and floor, and determine precisely the usable living space.

In a loft, one distinction is essential: not all the floor space is living space. The Loi Carrez (the French legal floor-area measurement) only counts areas where the ceiling height exceeds 1.80 m. Everything below that limit, along the sloping sides of the roof, physically exists but does not count in the official measurement.

In practice, a loft with 40 m² of floor space may offer only 25 to 30 m² of living space under the Loi Carrez, depending on the roof pitch. This is a crucial figure: it determines the added value of the project, the planning procedures and the room layout. The good news: the low-height areas, far from being wasted, become clever storage — built-in cupboards under the eaves, drawers, low bookcases — which give a loft room all its charm.

From the study stage, we draw up a clear plan distinguishing floor space, living space and gross floor area (the one that determines the permissions required). So you know exactly what you are gaining before the work starts.

Insulation is the number one item in a successful loft conversion. Under the roof, you face both summer heat and the Alpine winter cold: without high-performance insulation, the room becomes unliveable. There are two main techniques: insulating the roof slopes from the inside, with wool (mineral or bio-based) laid in one or two crossed layers, or external insulation using sarking, laid over the rafters when the roof covering is redone, which eliminates thermal bridges without reducing the interior volume.

Next comes light. To bring in daylight, there are several solutions depending on the configuration and the local plan (PLU): roof windows (Velux type), simple and cost-effective; dormers, which add volume and a traditional character much appreciated in Aix-les-Bains; or the flat-roofed dormer, which creates a valuable full-height area. The choice depends on the look you want and on local architectural requirements.

You also need to think about access: a comfortable staircase, straight, quarter-turn or spiral depending on the space available, that fits into the floor below without taking up too much area. Finally, electrics, heating and ventilation (mechanical ventilation) suited to the new room are installed, followed by partitions, plastering and finishes. This coordination of the trades is at the heart of our work: you will find all our services on our services page.

Converting a loft creates gross floor area, which triggers planning procedures. As a general rule: a prior declaration (déclaration préalable) is enough for 5 to 20 m² created (up to 40 m² in an urban zone covered by a local plan); beyond that, or if the house exceeds 150 m² in total after the work, a building permit is required. Adding Velux windows, dormers or flat-roofed dormers changes the external appearance and requires at least a prior declaration. In Aix-les-Bains, some areas are subject to specific requirements: we always check the PLU and submit the applications for you.

On the funding side, a loft conversion is the ideal opportunity to insulate. As soon as the work includes loft insulation, it becomes eligible for energy renovation grants: MaPrimeRénov' and Energy Savings Certificates (CEE) in particular. As an RGE CertiRénov-certified company (no. CR-2026-73-0095), Atelier NovAlp enables its clients to access these schemes and handles the grant applications for the insulation part.

As for budget, allow as a guide €500 to €1,200/m² for a complete conversion, finishes included. The price varies with the condition and type of roof structure, the insulation level, the number of openings, the staircase and floor strengthening. If your project is closer to extending upwards through the roof, our page on house extension prices, permits and timescales is a useful complement.